1. Field of the Invention
The present invention relates to a robot control device for controlling a robot moved according to a force applied to the robot. More particularly, the invention relates to a robot control device of a robot system that moves a robot on the basis of a force applied to the robot including a plurality of axes including at least one rotation axis.
2. Description of the Related Art
Direct teaching is known as a robot operation method for moving a robot by applying a force to the robot or a method for teaching a position by moving the robot. In such a case, force is applied in a direction to which the robot is desired to be moved to directly guide the robot, whereby the robot can be moved to a desired position and/or a desired posture on an orthogonal coordinate system.
Japanese Laid-open Patent Publication No. S56-85106 discloses a method for moving a position and a posture of a tip of a robot arm on the basis of a signal generated by a force detector when operating a manual operation unit of the force detector attached to the tip of the robot arm.
Japanese Laid-open Patent Publication No. H6-250728 discloses a direct teaching device. In this device, a force sensor attached to a robot detects an artificially applied force, and with the use of a signal of the force, a position and a posture of the robot are moved while moving a robot arm only in a specific direction on a Cartesian coordinate system.
In Japanese Laid-open Patent Publication No. 556-85106, the position and/or the posture of the tip of the robot arm on the orthogonal coordinate system is moved according to the force. Due to this, in the method of Japanese Laid-open Patent Publication No. S56-85106, the position of desired each axis cannot be moved during direct teaching.
In Japanese Laid-open Patent Publication No. H6-250728, when moving the robot by direct teaching, the moving direction of the robot is limited to the specific direction to improve operability. The specific direction is a direction associated with the position and/or the posture of the tip of the robot arm on the Cartesian coordinate system. Accordingly, Japanese Laid-open Patent Publication No. H6-250728 does not propose limiting a axis to be driven and the like, such as switching to control of each axis and driving of only a certain desired axis in direct teaching.
The present invention has been accomplished in view of such circumstances. It is an object of the invention to provide a robot control device that, when moving a position and/or a posture of a tip of a robot on an orthogonal coordinate system by moving the robot with application of a force to the tip of the robot arm, allows the tip thereof to be moved to a position to which it is difficult or impossible to move the tip thereof. The invention also further improves operability of such a robot control device.